The trend of rising home prices continues and is expected to carry on, but don’t expect double-digit gains as a norm, analysts say.

Home prices rose 12.1% in April, making it the 14th consecutive month of year-over-year increases, according to the latest CoreLogic Home Price Index. This is the largest annual gain since February 2006, a clear sign of a market in recovery mode.

However, double-digit gains are also cause for some concern, say experts who recall the unsustainable home price increases before the last housing downturn.

With some early post-recession investors in distressed single-family properties saying the market overheated and they’re pulling back, it appears a sudden shift is taking place in the market.

Although home prices have risen significantly these past few months, the housing market is still more than 20% below the April 2006 peak and several important factors could moderate rising prices.

Although rising home prices have created fear of another bubble, they have also helped 2.4 million underwater borrowers since the last quarter of 2011.

“Regaining equity creates options for those who might now consider selling their homes because they can close a transaction with enough cash to make a down payment on the next home,” said CoreLogic. “Higher prices also attract the interest of builders who see opportunity in increased demand. In both cases, a broader supply brings inventory more in balance with demand.”

The current January to April year-to-date increase in the supply of existing homes is the third highest in nearly 30 years, indicating a lessening in the inventory crunch.

“The increase in the supply in context of current tight underwriting standards should deflate the risk of any bubbles,” said CoreLogic.

Nationally, at today’s prices and rents, buying would be cheaper than renting until the 30-year fixed rate reaches 10.5%. San Jose has the lowest mortgage rate “tipping point” at 5.2%, followed by San Francisco and Honolulu.

The recent rise in mortgage rates has made buying a house a little more expensive: the increase in the 30-year fixed rate over the past month from 3.4% to 3.9% (Freddie Mac) raised the monthly payment on a $200,000 mortgage by $56, or 6%. However, because mortgage rates are still near long-term lows, and because prices fell so much after the housing bubble burst and remain low relative to rents even after recent price increases, buying is still much cheaper thanrenting. That means that the recent jump in rates doesn’t change the rent-versus-buy math much.

Rates are likely to keep rising, but how far must rates rise before buying a home starts to look expensive relative to renting? To answer this, we updated our Rent vs. Buy analysis with the latest asking prices and rents from March, April, and May 2013. Following our standard approach, we calculated the cost of buying and renting for identical sets of properties, including maintenance, insurance, taxes, closing costs, down payment, sales proceeds, and, of course, the monthly mortgage payment on a 30-year fixed-rate loan with 20% down and monthly rent. We assume people will stay in their homes for 7 years, deduct their mortgage interest and property tax payments at the 25% tax bracket, and get modest home price appreciation (see the detailed methodology and example here). Here’s what we found:

Buying remains cheaper than renting so long as mortgage rates are below 10.5%. At 3.9%, the current 30-year fixed rate according to Freddie Mac, buying is 41% cheaper than renting nationally. With a 5% mortgage rate, buying is still 34% cheaper than renting nationally. Mortgage rates would have to rise a huge amount – to 10.5% – to tip the math in favor of renting, which isn’t impossible. Rates were that high throughout the 1980s, but have been consistently below 10.5% since May 1990.

Each local market, of course, has its own mortgage rate “tipping point” when renting becomes cheaper than buying a home. At 3.9%, buying is cheaper than renting in all of the 100 largest metros, which means the tipping point is above 3.9% everywhere. The tipping point is lowest in San Jose, which would tip in favor of renting if rates reach 5.2%. It’s between 5% and 6% in San Francisco and Honolulu, and between 6% and 7% in New York and Orange County, CA.